Injection molding machines may be of such a design that the molding tool used therein can be replaced and removed as required, for example for the purposes of a change of molding format. The machine may thus ccmprise mold tool mounting plates each carrying support means for supporting the mold tool in a condition of precise alignment in respect of height, together with lateral guide means on the mounting plates for precise alignment of the mold tool in the lateral direction. The two portions making up the mold tool may then be clamped to the respective mounting plates by suitable clamping elements, while the mold tool portions and the mounting plates of the machine comprise connecting blocks with connections for supplying for example power, a temperature control medium for the mold tool and the like. The connecting blocks can thus be coupled together in the course of the operation of fitting the mold tool into the machine.
In arrangements of the general kind just described above, which thus provide for quick change and quick fitting of the mold tool, as disclosed for example in the article entitled `Produktionssteigerung beim Spritzgiessen durch Verringern der Maschinen-Stillstandzeiten` (Increasing production in injection molding by reducing machine down times), in Kunstoffe 70 (1980), pp. 128 to 131, and German laid-open application (DE-OS) No. 32 15 567, the bearing surfaces of the support means for aligning the mold tool in respect of height and the lateral guide surfaces are such that the tool must be in a substantially accurately aligned position with respect thereto, before it is inserted from above or from the side. The mold tool is moved within the guide arrangement formed by the support means and the lateral guide means, either by being lowered into position or by being pushed into position from the side, being displaced by means of a suitable drive arrangement in virtually parallel orientation with respect to the mold tool mounting plates. When the mold tool is fitted by being inserted frcm above, the movement for positioning the mold tool in the machine continues until the mold tool is resting on the support surfaces of the lower support means or, when the mold tool is fitted by being inserted from the side, the movement of the mold tool continues until it bears against an abutment which thus marks the correct position for the mold tool in the machine. After the mold tool has been fitted into its correct position in the machine, the high-speed clamping elements which are preferably actuated hydraulically are operated to engage projections provided on the sides of the mold tool, thereby to press the mold tool against the mounting plates of the machine. It will be appreciated that, in the course of the operation of moving the mold tool into position in the machine, the connections for temperature control medium, supply of power, blowing air and the like are also coupled together.
It will be appreciated that a necessary condition for effectively reducing the mold tool change times when using an arrangement as set forth above is that all the mold tools to be used, irrespective of their general format and size, must be of the same dimensions at their sides which are towards the mounting plates of the machine, so that, by virtue of the mold tool standing on the support surface of the lower support means and abutting laterally against the lateral guide means, the mold tool is positioned in the injection molding machine with the feedhead thereof being precisely aligned with respect to the feed duct in the mounting plate. That is advantageously achieved by virtue of an adaptor plate which is screwed on to the back of the mold tool, the clamping elements engaging over the adaptor plate when the mold tool is in the clamped position in the machine.
Although the above-discussed arrangement permits mold tools to be removed and replaced, for example for the purposes of changing the mold tool, in a relatively short period of time, the amount of time involved, particularly when handling large mold tools which may weigh several tons, is still quite substantial. This is because, in order to be able to move the mold tools into the guide arrangements provided on the mounting plates, the mold tool must be aligned with a very high degree of accuracy relative to the guides, before the movement of fitting the mold tool into the machine can be begun, and in addition the mold tool must be fitted into and removed from the machine with the utmost care in order to avoid damaging the guides and to prevent the mold tool from becoming jammed therein. As will be readily appreciated, that requires precision work on the part of the operating personnel, which is generally time-consuming. That is the more particularly where the mold tool is made up of two halves or portions which are fitted between the mounting plates jointly, that is to say, as an assembled mold tool, as in that case the mounting plates must also be moved apart precisely to the appropriate spacing to receive the mold tool therebetween.